An attachment connection for the heat exchanger media and an end retaining means for the tubes is provided by distributor heads that are clamped into place, so that the tubes are coupled at the end in a fluid media-tight manner and are axially braced. These distributor heads have concentrically distributed interspaces that extend the chambers between the tubes as far as the attachment connections.
A heat exchanger of this type is known from U.S. Pat. No. 4,146,088, Pain, to which German Patent Disclosure Document DE-A No. 27 48 183 corresponds. The patent discloses heads which taper toward their end, oriented toward the nest of tubes, and form terrace-like stepped seat faces, on which the tubes are mounted, with sealing rings interposed inbetween, and where they rest on axial stops of the distributor heads. In the interior, the distributor heads form two diametrically opposed, crescent-shaped collecting chambers, which communicate via fitting radial bores with the particular interspace to be connected between two adjacent tubes of the nest of tubes. At the face end of the distributor heads remote from the nest of tubes, the crescent-shaped collecting chambers merge with two connection stubs, located adjacent one another, for the two media that are to be put into mutual heat exchange. The axial bracing of the nest of tubes between the two terminal distributor heads is effected via a tie rod that is guided centrally through the innermost tube and joins the two distributor heads to one another.
For disassembling, e.g. for cleaning, the tubes of the nest must be removed from the outside inwardly, which makes them very difficult to grasp and pull apart. The design of the distributor heads dictates the arrangement regarding the flow cross sections formed between adjacent tubes of the nest. It is thus impossible to retrofit a heat exchanger of the known type for different applications requiring, for example, different flow cross sections. The known heat exchanger is held together by means of a central tie rod. Thus, an additional component is required, which is costly and heavy.
A very considerable disadvantage of the known construction, however, is that the media to be involved in heat exchange must be supplied to the distributor heads via diametrically opposite collecting chambers which, thus, are completely separate from one another. The distributor chambers therefore do not participate in the heat exchange at all. This represents a considerable waste of space and material. The opposed arrangement of the collecting chambers also means that at the transition from a collecting chamber to the adjoining heat exchanger chamber, which extends over the complete circular cross section, the medium distributes itself over the entire heat exchange chamber only gradually, so that at each end of such a heat exchange chamber a space is left with practically no flow through it, forming a dead space; within this dead space, solids entrained by the medium can collect and become compacted, a development that is enhanced still further by the fact that the respective heat exchange chamber and the aforementioned collecting chamber communicate only via one or a few radial bores, of narrow cross section, of the distributor head. Accordingly, risk or, rather, the probability results, that after extended periods of operation, the tubes of the nest will be stuck together from solids compacted between their ends, so that when the heat exchanger is to be disassembled, they can be taken apart only by using force.
Finally, the connection stubs for the heat exchange media that extend axially parallel from the known distributor heads necessitate connecting series-connected heat exchangers to one another via interposed pipe segments and the like, which again means a considerable expenditure of material, space and labor for assembly.